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Hurricane Lee Discussion Number  23
NWS National Hurricane Center Miami FL       AL132023
1100 PM AST Sun Sep 10 2023
 
There has been a wealth of data to dig though this evening for 
Hurricane Lee. Observations from both satellite imagery and this 
evening's NOAA-P3 mission indicate the hurricane has become more 
symmetric in both its convective pattern and wind field. On 
satellite, Lee has once again become more impressive with a warming 
eye surrounded by cold -65 to -75C eyewall cloud tops. In response, 
the subjective Dvorak estimates have been increasing, both T6.0/115 
kt from TAFB and SAB. In addition, a single closed eyewall of 25 n 
mi in diameter was reported by the NOAA aircraft, which has also 
been observed by the TDR data and an earlier 2151 UTC SSMIS 
microwave pass. The surface pressure has also been dropping, with 
the most recent dropsonde in the eye reporting 950 mb. However, the 
winds have yet to respond to the decreasing pressure, with peak 
flight-level winds of 108 kt, SFMR at 103 kt, and surface reduced 
TDR data also in the 100-105 kt range. All of the in-situ aircraft 
data supports maintaining an initial intensity of 105 kt this 
advisory. A Synthetic Aperture Radar (SAR) pass valid at 2213 UTC 
also showed a 105-kt peak wind, but with expanding 64-kt wind radii, 
which might explain why the winds have yet to respond to the 
pressure drop.
 
Track-wise, Lee continues to move west-northwestward, at 305/6 kt.
This motion is expected to generally continue with a further
slowdown in the forward motion now that the mid-level ridging
influencing the storms steering has shifted more northwest in front
of the hurricane. However, this ridge is expected to then become
eroded by an approaching deep-layer trough, allowing Lee to turn
northward into the weakness produced by the trough. The track
guidance this cycle is in fairly good agreement over the next 5
days, with the largest details still related to the forward motion
of Lee after it turns northward. The NHC track forecast is pretty
much on top of the prior one, continuing to favor the consensus
aids, and is roughly in between the leftward GFS and rightward
ECMWF model solutions. Users should be reminded to not focus on the
exact forecast track, especially given Lee's forecast size at the
longer range, and the average day 4 and 5 track errors are about
145 and 200 miles, respectively.
 
Data from an earlier NOAA G-IV mission sampling the environment 
around Lee indicated that the vertical wind shear that had been 
affecting the hurricane has mostly subsided, with the dropsonde data 
showing well-established outflow to the north, and a deep-layer of 
cyclonic flow to the south associated with Lee's broad and deep 
circulation. While it is difficult to predict the inner-core changes 
associated with the cyclone, most of the intensity guidance still 
suggests Lee will intensify further over the next day or so, with a 
120-kt peak predicted in 24 hours. Afterwards, as Lee continues to 
slow down, it may then begin to encounter its own cold wake due to 
its expanding wind field, and the hurricane is expected to begin 
gradually weakening. This weakening should be hastened by increasing 
southwesterly vertical wind shear after 72 h as the storm also 
traverses already cooled sea-surface temperatures by Franklin and 
Idalia last week. However, the model guidance also shows Lee's 34-kt 
and 50-kt wind field continuing to expand through the forecast 
period even as the hurricane gradually weakens.
 
KEY MESSAGES:
 
1. Dangerous surf and life-threatening rip currents will affect
portions of the northern Leeward Islands, the Virgin Islands, Puerto
Rico, Hispaniola, the Turks and Caicos Islands, the Bahamas, and
Bermuda through much of this week.
 
2. Lee could bring wind, rainfall, and high surf impacts to
Bermuda later this week.  Although it is too soon to determine the
specific timing and level of those impacts, interests on Bermuda
should monitor the latest forecasts for Lee.
 
3. It remains too soon to know what level of impacts, if any,
Lee might have along the U.S. East Coast and Atlantic Canada late
this week, especially since the hurricane is expected to slow
down considerably over the southwestern Atlantic.  Regardless,
dangerous surf and rip currents are expected along most of the U.S.
East Coast this week as Lee grows in size. Users should continue to
monitor updates to the forecast of Lee during the next several days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  11/0300Z 22.6N  62.2W  105 KT 120 MPH
 12H  11/1200Z 23.1N  63.1W  115 KT 130 MPH
 24H  12/0000Z 23.6N  64.4W  120 KT 140 MPH
 36H  12/1200Z 24.1N  65.5W  115 KT 130 MPH
 48H  13/0000Z 24.6N  66.4W  110 KT 125 MPH
 60H  13/1200Z 25.3N  67.2W  100 KT 115 MPH
 72H  14/0000Z 26.5N  67.7W   95 KT 110 MPH
 96H  15/0000Z 30.2N  67.9W   85 KT 100 MPH
120H  16/0000Z 35.5N  67.0W   70 KT  80 MPH
 
$$
Forecaster Papin
 
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